Microbial processes and bacterial populations associated to anaerobic treatment of sulfate-rich wastewater

A pilot-scale (1.2 m3) anaerobic sequencing batch biofilm reactor (ASBBR) containing mineral coal for biomass attachment was fed with sulfate-rich wastewater at increasing sulfate concentrations. Ethanol was used as the main organic source. Tested COD/sulfate ratios were of 1.8 and 1.5 for sulfate loading rates of 0.65–1.90 kgSO42−/cycle (48 h-cycle) or of 1.0 in the trial with 3.0 gSO42− l−1. Sulfate removal efficiencies observed in all trials were as high as 99%. Molecular inventories indicated a shift on the microbial composition and a decrease on species diversity with the increase of sulfate concentration. Beta-proteobacteria species affiliated with Aminomonas spp. and Thermanaerovibrio spp. predominated at 1.0 gSO42− l−1. At higher sulfate concentrations the predominant bacterial group was Delta-proteobacteria mainly Desulfovibrio spp. and Desulfomicrobium spp. at 2.0 gSO42− l−1, whereas Desulfurella spp. and Coprothermobacter spp. predominated at 3.0 gSO42− l−1. These organisms have been commonly associated with sulfate reduction producing acetate, sulfide and sulfur. Methanogenic archaea (Methanosaeta spp.) was found at 1.0 and 2.0 gSO42− l−1. Additionally, a simplified mathematical model was used to infer on metabolic pathways of the biomass involved in sulfate reduction

Vibration control of manipulators with flexible nonprismatic links using piezoelectric actuators and sensors

This work presents a tracking control model for a flexible nonprismatic link robotic manipulator using simultaneously motor torques and piezoelectric actuators. The dynamic model of the flexible manipulator is obtained in a closed form through the Lagrange equations. The control uses the motor torques for the joints tracking control and also to reduce the low-frequency vibration induced in the manipulator links. The stability of this control is guaranteed by the Lyapunov stability theory. Piezoelectric actuators and sensors are added for controlling vibrations with frequencies beyond the reach of motor torque control. The naturals frequencies are calculated by the finite element method, and the approximated eigenfunctions are interpolated by polynomials. Three eigenfunctions are used for the dynamics of the arm, while only two are used for the control. Numerical experiments on Matlab/Simulink are used to verify the efficiency of the control model

Simultaneous piezoelectric actuator and sensor placement optimization and control design of manipulators with flexible links using SDRE method

This paper presents a control design for flexible manipulators using piezoelectric actuators bonded on nonprismatic links. The dynamic model of the manipulator is obtained in a closed form through the Lagrange equations. Each link is discretized using finite element modal formulation based on Euler-Bernoulli beam theory. The control uses the motor torques and piezoelectric actuators for controlling vibrations. An optimization problem with genetic algorithm GA is formulated for the location and size of the piezoelectric actuator and sensor on the links. The natural frequencies and mode shapes are computed by the finite element method, and the irregular beam geometry is approximated by piecewise prismatic elements. The State-Dependent Riccati Equation SDRE technique is used to derive a suboptimal controller for a robot control problem. A state-dependent equation is solved at each new point obtained for the variables from the problem, along the trajectory to obtain a nonlinear feedback controller. Numerical tests verify the efficiency of the proposed optimization and control design

Anatase/rutile Mass Fraction Determination In Tio2 Nanoparticles Using Rietveld Refinement Aiming Applications In Water Purification

Given the growing demand for sanitation solutions, various techniques of wastewater treatment have been proposed. Among them, we highlight the use of photocatalysts. Among all alternative materials proposed for using in the photocatalytic process, crystalline titania has been one of the most used because it can be easily sensitized by ultraviolet light. However, studies indicate that its efficiency is dependent on the mass fraction of anatase and rutile phases present in the titania composition. This paper aims at the use of the Rietveld refinement for quantifying the mass fraction present in titania nanoparticles obtained by the flame aerosol method. X-Ray diffraction patterns were obtained from synthesized samples and compared with the analysis of a commercial sample (Degussa P-25). We observed that the methodology of flame aerosol is effective for controlling the growth of anatase and rutile phases by just controlling the gas flow in the burner. Fraction of anatase / rutile with relative errors smaller than 10% was obtained by Rietveld refinement.74p.57-67Engenharia Ambiental, Engenharia Mecânic

Heat shock response in bacteria with large genomes: lessons from rhizobia

Rhizobia are important soil bacteria due to their ability to establish nitrogen-fixing symbioses with legume plants. In this dual lifestyle, as free-living bacteria or as plant symbiont, rhizobia are often exposed to different environmental stresses. The present chapter overviews the current knowledge on the heat shock response of rhizobia, highlighting how these large genome bacteria respond to heat from a transcriptional point of view. Response to heat shock in rhizobia involves genome wide changes in the transcriptome that may affect more than 30% of the genome and involve all replicons. In addition to the expected upregulation of genes already known to be involved in stress response (dnaK, groEL, ibpA, clpB), the reports on the heat shock response in rhizobia also showed particular aspects of stress response in these resourceful bacteria. The transcriptional response to heat in rhizobia includes the overexpression of a large number of genes involved in transcription and carbohydrate transport and metabolism. Additional studies are needed in order to better understand the transcriptional regulation of stress response in bacteria with large genomes

Evaluation of carbonisation gas from coal and woody biomass and reduction rate of carbon composite pellets.

Carbon composite iron oxide pellets using semichar or semicharcoal were proposed from the measured results of the carbonisation gas release behaviour. The carbonisation was done under a rising temperature condition until arriving at a maximum carbonisation temperature Tc,max to release some volatile matter (VM). The starting point of reduction of carbon composite pellets using semicharcoal produced at Tc,max?=?823?K under the rising temperature condition was observed at the reduction temperature TR?=?833?K, only a little higher than Tc,max, which was the aimed phenomenon for semicharcoal composite pellets. As Tc,max increases, the emitted carbonisation gas volume increases, the residual VM decreases, and, as a whole, the total heat value of the carbonisation gas tends to increase monotonically. The effect of the particle size of the semicharcoal on the reduction rate was studied. When TR is higher than Tc,max, the reduction rate increases, as the particle size decreases. When TR is equal to Tc,max, there is no effect. With decreasing Tc,max, the activation energy Ea of semicharcoal decreases. The maximum carbonisation temperature Tc,max may be optimised for reactivity (1/Ea) of semicharcoal and the total carbonisation gas volume or the heat value

Surto de Trypanosoma vivax em rebanhos bovinos na Zona da Mata do estado de Pernambuco

Objetivou-se registrar a ocorrência e descrever os achados clínicos e hematológicos de surtos de tripanossomíase em bovinos em propriedades localizadas nos municípios de Timbaúba e Paudalho, Zona da Mata do estado de Pernambuco. Foram realizadas visitas às propriedades para coleta de dados sobre o histórico do rebanho além de informações sobre o manejo dos animais na propriedade, realização de exame clínico e coleta de material para hemograma, pesquisa de hematozoários e Reação em Cadeira da Polimerase. Clinicamente, os animais apresentavam mucosas hipocoradas, emaciação, havendo histórico de óbito em ambas as propriedades. Previamente ao manejo da ordenha era feita a aplicação de ocitocina, sendo ainda observada a presença de moscas hematófagas. Ao hemograma observou-se presença de anemia normocítica normocrômica e leucocitose por neutrofilia na maioria dos animais. Foi observada presença do protozoário Trypanosoma vivax no esfregaço sanguíneo e confirmados na PCR. Recomendou-se o tratamento com diaceturato de diminazene (10,5 mg/kg) em administração única. Conclui-se que o T. vivax, ocorre na região nordeste de maneira esporádica e que o manejo sanitário deficiente predispõe a ocorrência da enfermidade nos rebanhos

Appearance of Membrane Compromised, Viable But Not Culturable and Culturable Rhizobial Cells as a Consequence of Desiccation

For agricultural purposes, drought related stresses negatively affect the Rhizobiaceae in at least three ways. Firstly, rhizobial populations are affected by desertification of agricultural soils. Secondly, the quality of dry-base inocula, also called formula, is negatively affected by a drying step, and thirdly, rhizosphere bacteria protect crop-plants against drought. Although survival of cultivatable bacteria has been studied intensively in dry-base seed inocula and in-vitro, thus far research has only marginally addressed the bacterial cell, its cellular structures and physiology. Many questions remain regarding the sensing of and physiological response of rhizobia to desiccation. This review will focus on the three different fractions of cells after desiccation, the membrane compromised cells, the viable but not culturable cells and the culturable cells

Human eosinophil adhesion and degranulation stimulated with eotaxin and RANTES in vitro: Lack of interaction with nitric oxide

<p>Abstract</p> <p>Background</p> <p>Airway eosinophilia is considered a central event in the pathogenesis of asthma. The toxic components of eosinophils are thought to be important in inducing bronchial mucosal injury and dysfunction. Previous studies have suggested an interaction between nitric oxide (NO) and chemokines in modulating eosinophil functions, but this is still conflicting. In the present study, we have carried out functional assays (adhesion and degranulation) and flow cytometry analysis of adhesion molecules (VLA-4 and Mac-1 expression) to evaluate the interactions between NO and CC-chemokines (eotaxin and RANTES) in human eosinophils.</p> <p>Methods</p> <p>Eosinophils were purified using a percoll gradient followed by immunomagnetic cell separator. Cell adhesion and degranulation were evaluated by measuring eosinophil peroxidase (EPO) activity, whereas expression of Mac-1 and VLA-4 was detected using flow cytometry.</p> <p>Results</p> <p>At 4 h incubation, both eotaxin (100 ng/ml) and RANTES (1000 ng/ml) increased by 133% and 131% eosinophil adhesion, respectively. L-NAME alone (but not D-NAME) also increased the eosinophil adhesion, but the co-incubation of L-NAME with eotaxin or RANTES did not further affect the increased adhesion seen with chemokines alone. In addition, L-NAME alone (but not D-NAME) caused a significant cell degranulation, but it did not affect the CC-chemokine-induced cell degranulation. Incubation of eosinophils with eotaxin or RANTES, in absence or presence of L-NAME, did not affect the expression of VLA-4 and Mac-1 on eosinophil surface. Eotaxin and RANTES (100 ng/ml each) also failed to elevate the cyclic GMP levels above baseline in human eosinophils.</p> <p>Conclusion</p> <p>Eotaxin and RANTES increase the eosinophil adhesion to fibronectin-coated plates and promote cell degranulation by NO-independent mechanisms. The failure of CC-chemokines to affect VLA-4 and Mac-1 expression suggests that changes in integrin function (avidity or affinity) are rather involved in the enhanced adhesion.</p